Angela Collier
3 HN recommenders · recommended in 3 months, 2024
1:00:28 · 404K views · May 24, 2024
Angela Collier, a physicist, revisits her earlier dark matter video, explaining dark matter as a set of observations rather than a theory and discussing MOND comments.
HN points to her videos as a counterpoint to popular dark matter discussion, framing it as the discrepancy that needs explaining.
5 comments from Hacker News
Dark Matter is a name for set of observations that aren't explainable with currently accepted cosmological theory. There are many possible ideas of how Dark Matter problem can be solved. Why do you think making fun of specific idea of what might be the cause of Dark Matter problem or even the Dark Matter problem itself is problematic? Did suddenly the deficiencies of current state of science became not funny? Modifications to gravity are one of the possible solutions to Dark Matter problem (just as Machos and Wimps are) but not especially good or plausible ones and deserve being joked about just as much. You can learn more about the problem from this physicist: this video > Inflation has no influence on galaxy formation. That's completely not what I was talking about. I was saying that the era of rapid inflation that despite being postulated to be just a fraction of a second had immense impact on the shape of the universe can't be swept under the rug just because it's short and is already a kind of "Dark Time" when huge things were happening despite time barely passing. You could equally sensibly postulate that 500 million years since the Big Bang there was a fraction of a second when galaxy formation underwent accelerated progress that aged them few billion years and that explains early black holes and such. Hopefully it won't come to that and more sensible explanation of what JWST sees will prevail. It's true that "dark age" is not talked about in cosmology and is and invetion
If you've got the time, these YouTube videos are a nice counterpoint to a lot of popular communication and discussion on dark matter: Dark matter is not a theory: [LINK] That dark matter video aged like milk: this video the tl;dr is that "dark matter" is a bit of a misnomer. (But also a fun name so it's probably here to stay through sheer memetic momentum.) Dark matter is not actually a hypothesized kind of matter. Dark matter is just an unresolved discrepancy between theory and observation. I'll say that again: "dark matter" is not an attempt at explaining the discrepancy; dark matter is the discrepancy. There are some hypotheses that postulate some kind of as-yet-unobserved matter that could resolve the discrepancy, but these hypotheses are not the actual problem that we call "dark matter". And not all hypotheses postulate unobserved or exotic matter. Some of them suggest alternative physics, others suggest measurement error.
IANAP (physicist) The only the matter portion of the universe is 85% dark matter (26.8% of mass-energy content of the universe). As for the question; I don't think it's right to assume that dark matter really is exotic matter. It's just a set of observations. It's something that behaves like matter (with respect to density scaling) but only seems to interact gravitationally. Some theories posit that it's some unknown particles, others that they are primordial black holes, and some that gravity just behaves differently (MOND). I really enjoyed Dr Angela's videos on Dark Matter [1,2] [1] this video [2] [LINK]
Let's talk about the article and then dark matter, I guess: > We’ve always been taught that the fundamental constants of nature — like the speed of light or the charge of an electron — are unchanging. But what if they aren’t fixed after all? I mean, sure, what if? Honestly, if you can vary things like gravity, I don't think you need any additional components to explain the dark matter observations. > The CCC+TL model needs to provide testable predictions that can be confirmed or refuted through observations and experiments This step is important! Ok, so dark matter generally: this YouTuber [1](physicist/physics PhD) notes that there are many theories that explain the dark matter observations. But to her, "dark matter" is the data that we need to explain. Essentially: we have a bunch of weird observations where it looks like there's way more matter than we see. But the actual explanation for what it is, there are tons of those. So throw one more in the pile (this one says "oh there's no extra matter, the universal constants are different over there and light maybe moves slower as it travels farther") [1] this video
I also don't know why MOND remains so popular. Angela Collier talks about Dark Matter here: [LINK] And talks more about how often MOND is brought up in comments on her own video: this video